Hitherto, it has been known that reversal images are obtained by developing internal latent image type silver halide grains, which are composed of a core of silver halide doped with metal ions, chemically sensitized, or subjected to both treatment and a shell of the silver halide covering at least sensitivity sites of the core (hereinafter referred to as core/shell type grains), in which the surface of the shell is, if desired, chemically sensitized, in the presence of a fogging agent, or by a direct reversal process that an overall light-exposure is applied at the time of development. Such are described, for example, in U.S. Pat. Nos. 3,317,322 and 3,761,276, etc.
If such core/shell type silver halide grains are used, good reversal photographic characteristics can be obtained. However, such core/shell type silver halide emulsions have had a problem in that stability with the passage of time is unsatisfactory. Particularly, if subjected to severe conditions such as high temperature and high humidity, the reversal photographic characteristics easily deteriorate.
Further, if two or more kinds of core/shell type silver halide grains each having a different average grain size, are used for direct positive photographic light-sensitive materials in order to expand exposure latitude, the direct positive photographic light-sensitive materials exhibit a problem in that stability with the passage of time deteriorates even more rapidly. Moreover, if direct positive photographic light-sensitive materials are exposed to an atmosphere containing oxygen and moisture as a normal state during storage prior to use, this tendency is even more pronounced.